Method for estimating engine friction torque
First Claim
1. A method for estimating friction torque in an internal combustion engine having an electronic controller with repetitive control loops, the controller having memory storage registers that provide residence for a look-up table, the look-up table being characterized by at least two input variables, the method comprising the steps of:
- determining a reference model of engine friction torque using calibrated engine friction torque data following an engine start event before engine idle is achieved;
determining a deviation of engine friction torque from the reference model to estimate actual friction torque; and
adapting sites in the look-up table if the estimated engine friction torque determined in a current engine start event differs from estimated engine friction torque determined in a preceding engine start event.
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Abstract
Algorithms for real-time estimation of the engine friction torque in a vehicle powertrain are disclosed. Engine friction torque is estimated at start and at engine idle. Recursive and computationally efficient algorithms allow prediction of friction torque for a wide range of speeds and loads even with few new measured points by taking into account physical dependencies used for adaptation of the sites of the look-up tables (static maps). The algorithms make it possible to avoid drivability problems that could result from errors in estimating engine friction torque.
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Citations
12 Claims
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1. A method for estimating friction torque in an internal combustion engine having an electronic controller with repetitive control loops, the controller having memory storage registers that provide residence for a look-up table, the look-up table being characterized by at least two input variables, the method comprising the steps of:
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determining a reference model of engine friction torque using calibrated engine friction torque data following an engine start event before engine idle is achieved; determining a deviation of engine friction torque from the reference model to estimate actual friction torque; and adapting sites in the look-up table if the estimated engine friction torque determined in a current engine start event differs from estimated engine friction torque determined in a preceding engine start event.
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2. A method for estimating friction torque in an internal combustion engine having an electronic controller with repetitive control loops, the controller having memory storage registers that provide residence for a look-up table, the look-up table being characterized by at least an engine speed input variable and an indicated engine torque variable, the method comprising the steps of:
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determining a reference model of engine friction torque using calibrated engine friction torque data following an engine start event before engine idle is achieved; determining an estimated engine friction torque using current engine speed and indicated engine torque as variables; determining a deviation of engine friction torque from the reference model based on the current engine speed and indicated engine torque variables; and adapting sites in the look-up table if the estimated engine friction torque determined in a current engine start event differs from estimated engine friction torque determined in a preceding engine start event. - View Dependent Claims (3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method for estimating friction torque in an internal combustion engine having an electronic controller with repetitive control loops, the controller having memory storage registers that provide residence for algorithms in the form of a look-up table, the look-up table being characterized by at least an engine speed input variable and an indicated engine torque variable, the method comprising the steps of:
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measuring engine speed during an engine start event; measuring engine speed during an engine idle state following an engine start event; determining a reference model of engine friction torque using calibrated engine friction torque data based on indicated torque and measured engine speed at the time of an engine start event and an indicated torque and measured engine idle speed at the time engine idle is achieved; determining an estimated engine friction torque during a time interval between an engine start event and the time engine idle is achieved using current engine speed and indicated engine torque variables; determining a deviation of engine friction torque from the reference model based on current engine speed and indicated engine torque variables; and adapting sites in the look-up table if the estimated engine friction torque determined in a current engine start event differs from estimated engine friction torque determined in a preceding engine start event.
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Specification